Oldest Remnants of Earth’s Early Magnetic Field


  • Geologists at MIT and Oxford University have found ancient rocks in Greenland that bear the oldest remnants of Earth’s early magnetic field.


  • The rocks are about 3.7 billion years old and retain signatures of a magnetic field with a strength of at least 15 microtesla.
  • Today, Earth’s magnetic field measures around 30 microtesla.
  • The iron particles in these rocks effectively act as “tiny magnets” that can detect and record the Earth’s magnetic field.
  • The rocks were uncovered from the Isua supracrustal Belt in Greenland.
  • Scientists suspect that, early in its evolution, the Earth was able to foster life, in part due to an early magnetic field that was strong enough to retain a life-sustaining atmosphere and simultaneously shield the planet from damaging solar radiation.
  • Significance: This discovery can help scientists understand Earth’s early history and the factors that contributed to the emergence of life.
  • The detailed analysis could help measure early traces of Earth’s magnetic field in other places around the world, helping recreate its global shape and evolution through the planet’s 4.5 billion-year lifespan.
Supracrustal Belt

– The Supracrustal Belt has a special geology: It sits upon a thick layer of Earth’s crust that has protected it from tectonic activity and deformation for billions of years.

– The Isua supracrustal Belt is one of the oldest known rock formations on Earth, with some of its rocks dating back to around 3.7 to 3.8 billion years ago.

– This makes it a crucial site for studying the early Earth’s geological and environmental conditions.

– The Isua supracrustal Belt is located in southwestern Greenland, in a remote and inaccessible region.

Earth’s Magnetic Field

  • Earth’s magnetic field — also known as the geomagnetic field — is generated in the planet’s interior and extends out into space, creating a region known as the magnetosphere.
  • It is a protective shield generated by the movement of molten iron and nickel in its outer core.
  • This movement, called convection, creates electric currents, which in turn produce magnetic fields.
  • These magnetic fields combine to form the Earth’s overall magnetic field.
  • Significance: It extends from the planet’s interior out into space and helps protect the Earth from the harmful effects of solar wind and cosmic radiation.
  • The magnetic field also plays a crucial role in navigation, as it influences compass needles, allowing travelers to find their way based on magnetic north.
  • Without the magnetic field, life on Earth would not be possible as it shields us from the constant bombardment by charged particles emitted from the sun.